In MultiSSL mode (i.e. when more than one SSL backend is compiled
in), we cannot use the compile time flag `USE_NSS` as indicator that
the NSS backend is in use. As far as Metalink is concerned, the SSL
backend is only used for MD5, SHA-1 and SHA-256 calculations,
therefore one of the available SSL backends is selected at compile
time, in a strict order of preference.
Let's introduce a new `HAVE_NSS_CONTEXT` constant that can be used
to determine whether the SSL backend used for Metalink is the NSS
backend, and use that to guard the code that wants to de-initialize
the NSS-specific data structure.
Ref: #1848

With the recently introduced MultiSSL support multiple SSL backends
can be compiled into cURL That means that now the order of the SSL
One option would be to use the same SSL backend as was configured
via `curl_global_sslset()`, however, NTLMv2 support would appear
to be available only with some SSL backends. For example, when
eb88d77 (ntlm: Use Windows Crypt API, 2014-12-02) introduced
support for NTLMv1 using Windows' Crypt API, it specifically did
*not* introduce NTLMv2 support using Crypt API at the same time.
So let's select one specific SSL backend for NTLM support when
compiled with multiple SSL backends, using a priority order such
that we support NTLMv2 even if only one compiled-in SSL backend can
be used for that.
Ref: #1848

... as the test cases themselves do that and it makes it easier to add
crazy test cases.
Test 800 updated to use user name + password that need quoting.
Test 856 updated to trigger an auth fail differently.
Ref: #1902

In some cases the RSA key does not support verifying it because it's
located on a smart card, an engine wants to hide it, ...
Check the flags on the key before trying to verify it.
OpenSSL does the same thing internally; see ssl/ssl_rsa.c
Closes#1904

Before merging in the oss-fuzz corpora from Google, there are some changes
to the fuzzer.
- Add a read corpus script, to display corpus files nicely.
- Change the behaviour of the fuzzer so that TLV parse failures all now
go down the same execution paths, which should reduce the size of the
corpora.
- Make unknown TLVs a failure to parse, which should decrease the size
of the corpora as well.
Closes#1881

... instead of truncating them.
There's no fixed limit for acceptable cookie names in RFC 6265, but the
entire cookie is said to be less than 4096 bytes (section 6.1). This is
also what browsers seem to implement.
We now allow max 5000 bytes cookie header. Max 4095 bytes length per
cookie name and value. Name + value together may not exceed 4096 bytes.
Added test 1151 to verify
Bug: https://curl.haxx.se/mail/lib-2017-09/0062.html
Reported-by: Kevin Smith
Closes#1894

Prior to this change it appears the SOCKS5 port parsing was erroneously
used for the SOCKS4 error message, and as a result an incorrect port
would be shown in the error message.
Bug: #1892
Reported-by: Jackarain@users.noreply.github.com

Schannel can only encrypt a certain amount of data at once. Instead of
failing when too much data is to be sent at once, send as much data as
we can and let the caller send the remaining data by calling send again.
Bug: https://curl.haxx.se/mail/lib-2014-07/0033.htmlCloses#1890